The present invention is directed to software and method of determining the end-of-dialing of a telephone number made on a standard, land-type telephone coupled to a cellular network via a cellular interface apparatus. Cellular interfaces that couple a standard, land-type telephone, such as a POTS (Plain Old Telephone System) phone or facsimile machine, and the like, to a cellular network are disclosed in commonly-owned U.S. Pat. Nos. 4,658,096, and 4,737,975, which patents are incorporated by reference herein. The prior-art cellular interface systems determine when the last digit of a telephone number has been dialed, or entered, based on three methods: Digit count, time-out, and manual send. In the digit-count method, the apparatus automatically counts the number of digits dialed, and upon reaching a preset limit, will trigger an automatic SEND signal to send the telephone number to the transceiver for completing the call over the cellular system. This method also relies upon digit recognition, such that, if the digit 1 is dialed first, the apparatus will know to wait for the input of eleven digits before triggering the automatic SEND signal. The problem with this method is that the count of digits for which the automatic SEND signal is triggered will typically vary from one country to another, and requires relatively sophisticated software.
The second method, time-out, relies upon a preset lull after the dialing of a digit, and if that preset lull has been reached, it is automatically assumed that the last digit of the telephone number has been entered, and the automatic SEND signal is then generated. This method suffers from the drawback that the generation of the SEND signal is relatively much longer after the entry of the last digit as compared switch the first, digit-count method. The lull time-out may run from two seconds up to twenty seconds. The programmable timer of this method is circuitry which has user or factory-adjustable parameters. The time-period is factory set to a value, nominally 3 seconds, and is stored in the radio EEPROM. Depending on customer requirements, it can be set over a wide range of delays (typical values have been from 2 to 10 seconds). If the value is set too long, the customer may wonder why the phone is waiting; if it is set too short, the phone will mis-dial with an incomplete number, if the customer pauses too long.
The third, manual method relies upon the user of the telephone to press a predetermined "SEND" button on the telephone, such as the pound key or star key, or the like, after having entered the last digit of the telephone number, in order to activate the SEND signal. An alternative version of this is the use of a hook flash which will cause immediate generation of a SEND command. The timing of a hook flash is elusive to many people. If it is too quick, it is not recognized by the system; if it is too long, the telephone will hang up.
According to the present invention, a new method is used, in conjunction with one or more of the three prior-art methods outlined above, for accelerating the generation of the automatic SEND signal for those telephone numbers that have been previously dialed on the telephone.